A selective and potent CXCR3 antagonist SCH 546738 attenuates the development of autoimmune diseases and delays graft rejection.

BACKGROUND: The CXCR3 receptor and its three interferon-inducible ligands (CXCL9, CXCL10 and CXCL11) have been implicated as playing a central role in directing a Th1 inflammatory response. Recent studies strongly support that the CXCR3 receptor is a very attractive therapeutic target for treating autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis and psoriasis, and to prevent transplant rejection. We describe here the in vitro and in vivo pharmacological characterizations of a novel and potent small molecule CXCR3 antagonist, SCH 546738. RESULTS: In this study, we evaluated in vitro pharmacological properties of SCH 546738 by radioligand receptor binding and human activated T cell chemotaxis assays. In vivo efficacy of SCH 546738 was determined by mouse collagen-induced arthritis, rat and mouse experimental autoimmune encephalomyelitis, and rat cardiac transplantation models. We show that SCH 546738 binds to human CXCR3 with a high affinity of 0.4 nM. In addition, SCH 546738 displaces radiolabeled CXCL10 and CXCL11 from human CXCR3 with IC50 ranging from 0.8 to 2.2 nM in a non-competitive manner. SCH 546738 potently and specifically inhibits CXCR3-mediated chemotaxis in human activated T cells with IC90 about 10 nM. SCH 546738 attenuates the disease development in mouse collagen-induced arthritis model. SCH 546738 also significantly reduces disease severity in rat and mouse experimental autoimmune encephalomyelitis models. Furthermore, SCH 546738 alone achieves dose-dependent prolongation of rat cardiac allograft survival. Most significantly, SCH 546738 in combination with CsA supports permanent engraftment. CONCLUSIONS: SCH 546738 is a novel, potent and non-competitive small molecule CXCR3 antagonist. It is efficacious in multiple preclinical disease models. These results demonstrate that therapy with CXCR3 antagonists may serve as a new strategy for treatment of autoimmune diseases, including rheumatoid arthritis and multiple sclerosis, and to prevent transplant rejection.

Targeting the CB2 receptor for immune modulation.

Early work on the biology of the components of Cannabis sativa showed evidence for a potential influence on immune regulation. With the discovery of a peripheral cannabinoid receptor associated with immune cells, many laboratories have sought to link the immunoregulatory activities of cannabinoid compounds with this receptor, hoping that such compounds would lack the psychoactive effects of marijuana and other nonspecific cannabinoid agonists. In this report, the authors investigate the role of the cannabinoid CB2 receptor in immune regulation, with particular emphasis on compounds shown to regulate immune cell recruitment. The authors conclude by using the immune cell recruitment model to rationalise cannabinoid CB2 receptor-specific effects in modulating immune disease, particularly the increasing evidence for its role in experimental autoimmune encephalomyelitis and in influencing bone density.

Blocking ion channel KCNN4 alleviates the symptoms of experimental autoimmune encephalomyelitis in mice.

The KCNN4 potassium-ion channel has been reported to play an important role in regulating antigen-induced T cell effector functions in vitro. This study presents the first evidence that a selective KCNN4 blocker, TRAM-34, confers protection against experimental autoimmune encephalomyelitis (EAE) in the mouse model. Treatment with the KCNN4 blocker did not prevent infiltration of T cells in the spinal cord, but resulted in the reduction of both the protein and the message levels of TNF-alpha and IFN-gamma as well as the message levels of several other pro-inflammatory molecules in the spinal cord. Plasma concentrations of TRAM-34 within a 24-h period were between the in vitro IC(50) and IC(90) values for the KCNN4 channel. The effect of TRAM-34 was reversible, as indicated by the development of clinical EAE symptoms within 48 h after withdrawal of treatment. In summary, our data support the idea that KCNN4 channels play a critical role in the immune response during the development of MOG-induced EAE in C57BL/6 mice.